NOS1-mediated macrophage and endothelial cell interaction in the progression of atherosclerosis.

Atherosclerosis is a chronic inflammatory disease arising due to an imbalance in lipid metabolism and maladaptive immune response driven by the accumulation of cholesterol-laden macrophages in the artery wall. Interactions between monocytes/macrophages and endothelial cells play an essential role in the pathogenesis of atherosclerosis. In our current study, nitric oxide synthase 1 (NOS1)-derived nitric oxide (NO) has been identified as a regulator of macrophage and endothelial cell interaction. Oxidized LDL (OxLDL) activates NOS1, which results in the expression of CD40 ligand in macrophages. OxLDL-stimulated macrophages produce some soluble factors which increase the CD40 receptor expression in endothelial cells. This increases the interaction between the macrophages and endothelial cells, which leads to an increase in the inflammatory response. Inhibition of NOS1-derived NO might serve as an effective strategy to reduce foam cell formation and limit the extent of atherosclerotic plaque expansion.

Macrophage neuronal nitric oxide synthase (NOS1) controls the inflammatory response and foam cell formation in atherosclerosis.

Vascular inflammation plays a decisive role in the formation of foam cells and in the pathophysiology of atherosclerosis. However, the underlying mechanisms of these processes are not clearly understood. Macrophages engulf oxidized low-density lipoproteins (OxLDLs) via a scavenger receptor (SR), an event that mediates the elaboration of proinflammatory cytokines to initiate necrotic core formation in atherogenic plaques. In this study, we demonstrate that Nitric oxide synthase 1 (NOS1)-derived nitric oxide (NO) promotes OxLDL uptake and enhances the release of proinflammatory cytokines by macrophages. Conversely, we show that NOS1 inhibition by N(G)-nitro-L-arginine methyl ester (L-NAME) suppresses OxLDL uptake and proinflammatory cytokine expression. Current studies indicate that NOS1 plays a crucial role in vascular inflammation and in the progression of atherosclerosis. Therefore, interference with NOS1 enzymatic activity should serve as an effective strategy to reduce foam cell formation and limit the extent of atherosclerotic plaque expansion.

Tumor-derived exosomes in the regulation of macrophage polarization.

BACKGROUND: This review focuses on exosomes derived from various cancer cells. The review discusses the possibility of differentiating macrophages in alternatively activated anti-inflammatory pro-tumorigenic M2 macrophage phenotypes and classically activated pro-inflammatory, anti-tumorigenic M1 macrophage phenotypes in the tumor microenvironment (TME). The review is divided into two main parts, as follows: (1) role of exosomes in alternatively activating M2-like macrophages-breast cancer-derived exosomes, hepatocellular carcinoma (HCC) cell-derived exosomes, lung cancer-derived exosomes, prostate cancer-derived exosomes, Oral squamous cell carcinoma (OSCC)-derived exosomes, epithelial ovarian cancer (EOC)-derived exosomes, Glioblastoma (GBM) cell-derived exosomes, and colorectal cancer-derived exosomes, (2) role of exosomes in classically activating M1-like macrophages, oral squamous cell carcinoma-derived exosomes, breast cancer-derived exosomes, Pancreatic-cancer derived modified exosomes, and colorectal cancer-derived exosomes, and (3) exosomes and antibody-dependent cellular cytotoxicity (ADCC). This review addresses the following subjects: (1) crosstalk between cancer-derived exosomes and recipient macrophages, (2) the role of cancer-derived exosome payload(s) in modulating macrophage fate of differentiation, and (3) intracellular signaling mechanisms in macrophages regarding the exosome's payload(s) upon its uptake and regulation of the TME. EVIDENCE: Under the electron microscope, nanoscale exosomes appear as specialized membranous vesicles that emerge from the endocytic cellular compartments. Exosomes harbor proteins, growth factors, cytokines, lipids, miRNA, mRNA, and DNAs. Exosomes are released by many cell types, including reticulocytes, dendritic cells, B-lymphocytes, platelets, mast cells, and tumor cells. It is becoming clear that exosomes can impinge upon signal transduction pathways, serve as a mediator of signaling crosstalk, thereby regulating cell-to-cell wireless communications. CONCLUSION: Based on the vesicular cargo, the molecular constituents, the exosomes have the potential to change the fate of macrophage phenotypes, either M1, classically activated macrophages, or M2, alternatively activated macrophages. In this review, we discuss and describe the ability of tumor-derived exosomes in the mechanism of macrophage activation and polarization.

NOS1-derived nitric oxide facilitates macrophage uptake of low-density lipoprotein.

Foam cell formation is a hallmark event during atherosclerosis. The current paradigm is that lipid uptake by a scavenger receptor in macrophages initiates necrosis core formation that characterizes atherosclerosis. We report that NOS1-derived nitric oxide (NO) facilitates low-density lipoprotein (LDL) uptake by macrophages independent of the inflammatory response. LDL uptake could be dramatically suppressed by NOS1 specific inhibitor 1-(2-trifluoromethylphenyl) imidazole (TRIM). Importantly, the notion that NOS1 can mediate uptake of lipoproteins suggests that the foam cell formation is regulated by NOS1-derived NO-mediated mechanism. This is a novel study involving NOS1 as a critical player of foam cell formation and reveals much about the key molecular proteins involved in atherosclerosis. Targeting NOS1 would be a useful strategy in reducing LDL uptake by macrophages and hence dampening the atherosclerosis progression.

Repurposing Thioridazine (TDZ) as an anti-inflammatory agent.

Nuclear factor-kB (NF-kB) is a crucial transcription factor in the signal transduction cascade of the inflammatory signaling. Activation of NF-κB depends on the phosphorylation of IκBα by IκB kinase (IKKß) followed by subsequent ubiquitination and degradation. This leads to the nuclear translocation of the p50- p65 subunits of NF-κB, and further triggers pro-inflammatory cytokine gene expression. Thus, in the need of a more effective therapy for the treatment of inflammatory diseases, specific inhibition of IKKß represents a rational alternative strategy to the current therapies. A computer-aided drug identification protocol was followed to identify novel IKKß inhibitors from a database of over 1500 Food and Drug Administration (FDA) drugs. The best scoring compounds were compared with the already known high-potency IKKß inhibitors for their ability to bind and inhibit IKKß by evaluating their docking energy. Finally, Thioridazinehydrochloride (TDZ), a potent antipsychotic drug against Schizophrenia was selected and its efficiency in inhibiting IκBα protein degradation and NF-κB activation was experimentally validated. Our study has demonstrated that TDZ blocks IκBα protein degradation and subsequent NF-κB activation to inhibit inflammation. Thus, it is a potential repurposed drug against inflammation.

Heterotrimeric complex of p38 MAPK, PKCδ, and TIRAP is required for AP1 mediated inflammatory response.

Inflammation could be described as a physiological response of the body to tissue injury, pathogen invasion, and irritants. During the inflammatory phase, cells of both the innate as well as adaptive immune system are activated and recruited to the site of inflammation. These mediators are downstream targets for the transcription factors; activator protein-1 (AP1), nuclear factor kappa-light-chain-enhancer (NF-κB), signal transducers and activators of transcription factors (STAT1), as well as interferon regulatory factors (IRFs), which control the expression of most immunomodulatory genes. There is a significant increase in active p38 mitogen-activated protein kinase (p38MAK) immediately after lipopolysaccharide (LPS) stimulation, which results in the activation of AP-1 transcription factor and expression of proinflammatory cytokines, IL-12 and IL-23. We studied the novel mechanism of p38 MAPK activation through the formation of a heterotrimeric complex of Protein kinase C delta type (PKCδ), Toll-Interleukin 1 Receptor (TIR) Domain Containing Adaptor Protein (TIRAP), and p38 proteins. TIRAP serves as an adaptor molecule which brings PKCδ and p38 in close proximity. The complex facilitates the activation of p38MAPK by PKCδ. Therefore, we propose that disruption of the heterotrimeric complex may be a good strategy to dampen the inflammatory response. Structure-based design of small molecules or peptides targetting PKCδ-TIRAP or TIRAP-p38 interfaces would be beneficial for therapy in AP1 mediated inflammatory diseases.

The TLR4-NOS1-AP1 signaling axis regulates macrophage polarization.

OBJECTIVE: Macrophages polarize to proinflammatory M1 or anti-inflammatory M2 states with distinct physiological functions. This transition within the M1-M2 phenotypes decides the nature, duration and severity of an inflammatory response. Although there is a substantial understanding of the fate of these phenotypes, the underlying molecular mechanism of transition within the M1-M2 phenotypes is not well understood. We have investigated the role of neuronal nitric oxide synthase (NOS1)-mediated regulation of activator protein 1 (AP-1) transcription factor in macrophages as a critical effector of macrophage phenotypic change. MATERIALS AND METHODS: Raw 264.7 and THP1 macrophages were stimulated with LPS (250 ng/ml) to activate the inflammatory signaling pathway. We analyzed the effect of pharmacological NOS1 inhibitor: TRIM (1-(2- Trifluoromethylphenyl) imidazole) on LPS-induced inflammatory response in macrophages. RESULTS: We determined that NOS1-derived nitric oxide (NO) facilitate Fos and Jun interaction which induces IL-12 & IL-23 expression. Pharmacological inhibition of NOS1 inhibits ATF2 and Jun dimer. Switching of Fos and Jun dimer to ATF2 and Jun dimerization controls phenotype transition from IL-12high IL-23high IL-10low to IL-12low IL-23lowIL-10high phenotype, respectively. CONCLUSION: These findings highlight a key role of the TLR4-NOS1-AP1 signaling axis in regulating macrophage polarization.

Potential therapeutic targets for inflammation in toll-like receptor 4 (TLR4)-mediated signaling pathways.

Inflammation is set off when innate immune cells detect infection or tissue injury. Tight control of the severity, duration, and location of inflammation is an absolute requirement for an appropriate balance between clearance of injured tissue and pathogens versus damage to host cells. Impeding the risk associated with the imbalance in the inflammatory response requires precise identification of potential therapeutic targets involved in provoking the inflammation. Toll-like receptors (TLRs) primarily known for the pathogen recognition and subsequent immune responses are being investigated for their pathogenic role in various chronic diseases. A mammalian homologue of Drosophila Toll receptor 4 (TLR4) was shown to induce the expression of genes involved in inflammatory responses. Signaling pathways via TLR4 activate various transcription factors like Nuclear factor kappa-light-chain-enhancer (NF-κB), activator protein 1 (AP1), Signal Transducers and Activators of Transcription family of transcription factors (STAT1) and Interferon regulatory factors (IRF's), which are the key players regulating the inflammatory response. Inhibition of these targets and their upstream signaling molecules provides a potential therapeutic approach to treat inflammatory diseases. Here we review the therapeutic targets involved in TLR-4 signaling pathways that are critical for suppressing chronic inflammatory disorders.

Common and uncommon adult unilateral renal masses other than renal cell carcinoma.

Many different masses can involve the kidney other than the commonly encountered renal cell carcinoma (RCC). The purpose of this article is to review the characteristic clinical and imaging findings of common and uncommon masses that predominantly present unilaterally in the adult patient, other than RCC. Awareness of such lesions and knowing the clinical scenario is important for appropriate diagnosis and management, especially in a multidisciplinary care setting.

Common and uncommon bilateral adult renal masses.

Masses can involve the kidney unilaterally or bilaterally. The purpose of this article is to review common and uncommon adult renal masses that present bilaterally. Clinical and imaging findings are described. Renal masses that present in a bilateral fashion can have particular clinical and imaging characteristics and knowledge of their presentation enables appropriate diagnosis and management, especially in a multidisciplinary care setting. More commonly found bilateral renal masses that are discussed include metastasis, lymphoproliferative disorders, adult polycystic kidney disease, angiomyolipomas, renal infracts and renal abscesses. Less common bilateral renal masses include transitional cell carcinoma, oncocytoma, and hematomas.

Comparison of half-dose and full-dose gadolinium MR contrast on the enhancement of bone and soft tissue tumors.

OBJECTIVE: To evaluate the effect of half-dose intravenous gadolinium contrast on the enhancement of bone and soft tissue tumors. MATERIALS AND METHODS: This study is HIPAA compliant and informed consent was waived by the institutional review board. An institutional database search was performed over a 1-year period for patients with full- and half-dose MR examinations performed for musculoskeletal oncologic indications. Examination pairs that were identical with regard to field strength and presence or absence of fat saturation were included, resulting in 29 paired examinations. When multiple, the lesion that was best delineated and enhanced well on the first examination in the pair was chosen, yielding 17 bone and 12 soft tissue. Five musculoskeletal radiologists blinded to dosages were asked to assess for a difference in enhancement when comparing the lesion on both examinations and to rate the degree of difference on a three-point scale. They were also asked to identify the examination on which the lesion enhanced less (tallied as low dose). Results were analyzed with the exact binomial test. RESULTS: The readers perceived an enhancement difference in 41% (59/145) of studies (p = 0.03) and the majority were rated as "mild" (66%, 39/59). The readers did not accurately identify the low-dose examinations (54% correctly identified, 32/59, p = 0.60). CONCLUSIONS: Half-dose gadolinium enhancement of lesions could not be accurately distinguished from full-dose enhancement upon review of the same lesion imaged at both concentrations.

Voxel-based analysis of MRI detects abnormal visual cortex in children and adults with amblyopia.

Amblyopia, sometimes called "lazy eye," is a relatively common developmental visual disorder well characterized behaviorally; however, the neural substrates associated with amblyopia in humans remain unclear. We hypothesized that abnormalities in the cerebral cortex of subjects with amblyopia exist, possibly as a result of experience-dependent neuronal plasticity. Anatomic magnetic resonance imaging (MRI) and psychophysical vision testing was carried out on 74 subjects divided into two age ranges, 7-12 years and 18-35 years, and three diagnoses, strabismic amblyopia, anisometropic amblyopia, and normal vision. We report a behavioral impairment in contrast sensitivity for subjects with amblyopia, consistent with previous reports. When the high-resolution MRI brain images were analyzed quantitatively with optimized voxel-based morphometry, results indicated that adults and children with amblyopia have decreased gray matter volume in visual cortical regions, including the calcarine sulcus, known to contain primary visual cortex. This finding was confirmed with a separate region-of-interest analysis. For the children with amblyopia, additional gray matter reductions in parietal-occipital areas and ventral temporal cortex were detected, consistent with recent reports that amblyopia can result in spatial location and object processing deficits. These data are the first to provide possible neuroanatomic bases for the loss of binocularity and visual sensitivity in children and adults with amblyopia.